If, in a conventional power supply device 100A (FIG. 9) that controls output waveforms by means of a control unit CPU, an overcurrent detection circuit XA detects an overcurrent in an output circuit OCA (for example, a bridge circuit) based on an overcurrent threshold value THO, timing (and period) for turning off the output circuit OCA (suspending an output of a drive signal DS from a driver circuit DCA (fixing the drive signal DCA at a “Low” level)) is determined by a time constant circuit TA, which is hardware, using a CR time constant (FIG. 10) (for example, see Patent Document 1).
The conventional power supply device 100A therefore is likely to be affected by temperature and accuracy.
If the control unit CPU controls all operations for turning on or off the output circuit OCA based on overcurrent detection results in the conventional power supply device 100A, a problem arises in that as the switching frequency becomes higher, the processing load of the control unit CPU increases.